For nearly three years, he was the alleged kingpin of the world’s largest online drugs supermarket. Hiding behind the pseudonym of Dread Pirate Roberts, he ran a network that allowed thousands of dealers to sell drugs worth $1.2bn and was prepared to use violence to protect his privacy, according to the FBI. Yet the very public image of the man named by US law enforcement on Wednesday was starkly different: he openly talked online of his hopes, his heartbreaks and his desire to make a “substantial positive impact on the future of humanity”.

Ross William Ulbricht – who will appear in a US courtroom on Friday – was a libertarian activist who was obsessed by money and whose widespread internet profile is all the more remarkable since he was also one of the most wanted men in the US. He even left a telephone number on YouTube as he advertised his truck for sale last year.

In a life laid out with great openness, the physics graduate accused of drugs offences, computer hacking and money laundering, talks about his youthful experimentation with drugs and his passion for Eastern philosophy.

The 29-year-old was arrested on Wednesday after a two-year infiltration by the FBI of the Silk Road website that made him millions of pounds. He is also accused in the US state of Maryland of a failed hit on a blackmailer who threatened to expose users of the site unless he was paid $500,000 (£309,000).

His family and friends expressed astonishment at the charges against him as his life lived in public gave few hints as to his alleged involvement as a major player in the criminal underworld. “He is a really stellar, good person and very idealistic,” said his mother, Lyn Lacava. “I know he never meant to hurt anyone.”

Ulbricht’s interests on YouTube point to his libertarian outlook, his support for Ron Paul – the US presidential candidate and intellectual behind the right-wing Tea Party movement – and apparent like of the 1980s music of British band ELO.

He played drums for an African performance group, and belonged to a salsa dancing class at the University of Texas, according to the Washington Post, and had a keen interest in yoga, camping and partying.

In a 35-minute interview with a friend, he talks of taking AMT – a one-time legal psychedelic drug – and appeared to liken his youthful drug experiences to “a cannonball”.

But the recording, for a collection of tales of ordinary US life, gave few hints about how he is alleged to have made huge sums in commissions from drug sales. However, he expresses concerns over the role of government interference of the internet. “I feel like the world is in flux for sure,” he says. “You have the UN telecommunications department trying to create global rules for the internet and global governance emerging – crazy times.”

Ulbricht also had a Facebook page and accounts with Twitter and LinkedIn, where he writes of his changing philosophy after completing his work as a physicist.

“The most widespread and systemic use of force is amongst institutions and governments, so this is my current point of effort,” he said. “The best way to change a government is to change the minds of the governed. To that end, I am creating an economic simulation to give people a first-hand experience of what it would be like to live in a world without the systemic use of force.”

In July, customs agents intercepted fake documents with Ulbricht’s photo on them but when confronted at his San Francisco home he refused to answer questions, according to the FBI papers filed in a US court. The papers revealed that agents had been buying drugs from the site since 2011 before finally tracking down Ulbricht.

He was arrested on Tuesday afternoon in a branch of San Francisco’s public library while online on his laptop talking about the Silk Road with someone helping the FBI, authorities said. Librarians said they heard a loud commotion in the science fiction section of the library and saw a young man, who appeared to offer no resistance, pushed up against a floor-to-ceiling window by plain-clothes FBI agents as they handcuffed him.

The website, Silk Road, allowed users to anonymously browse through nearly 13,000 listings under categories like “Cannabis”, “Psychedelics” and “Stimulants” before making purchases using the electronic currency Bitcoin. One listing for heroin promised buyers “all rock, no powder, vacuum-sealed and stealth shipping”, and had a community forum below where one person commented: “Quality is superb.”

The website, whose other categories included “Erotica” and “Fireworks”, protected users with an encryption technique called onion routing, designed to make it “practically impossible to physically locate the computers hosting or accessing websites on the network”, court papers said.

The arrest marks a success for the authorities who have traditionally been seen as leaden-footed against the fast-changing nature of cyber-crime. “The FBI are definitely catching up and getting very, very good,” said Jay Abdallah, a network security consultant for Invensys. “But it’s always going to be cops and robbers and who has the newest technology and the smartest people.”